Method and apparatus for wireless signaling



F. H. KROGER.

METHOD AND APPARATUS FOR WIRELESS SIGNALING.

APPLICATION FILED AUG-2. 1915.

1,365,787. Patented Jan. 18,1921.

NN NN I i FIG.2 E i i E i /0 FIG-3 t if 42 WITNESSES INVENTOR UNITED sures.

PATENT omen.

FRED E. KROGER, OF BROOKLYN, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS, '10 INTERNATIONAL RADIO TELEGRAPH COMPANY, A CORPORATION 01 DELA- WARE.

nm'rnon AND APPARATUS non WIRELESS SIGNALING.

Patented Jan. 18, 1921.

Application filed August 2, 1915. Serial No. 43,182.

To all whom it may concern:

Be it known that I, FRED H. Kaoenn, a resident of Brookl n, in the county. of Kings and State of New ork, have invented a new and useful Improvement in Methods and Apparatus for Wireless Signaling, of which the following is a specification.

This invention relates to a method of an apparatus for generating radio signals by the use of a quenched-spark gap.

The-object of the inventioni's a more perfect tone control so as to obtain in the receiver a substantially pure or unvarying note when using a quenched spark gap in the transmitting apparatus, the purity of the note being independent of exact adjustment of the voltage of the generator, or of the frequency or coupling value in the oscillation circuits; and enabling the generator to be worked at a low excitation value.

In the drawings, which represent one embodiment of the invention, Figure 1 is a diagrammatic view of the circuits; Fig. 2 is a diagram showing the fall of potential across the spark gap when my improved.

spark controlcircuit is omitted; and Fig. 3

' is a similar view showing the potential curve lation transformer, the secondary 9 ofwhich is in the antennacircuit. The units of the primary oscillating circuit are all connected in series. Thespark control device shown comprises a step-up transformer whose primary 11 is in the power circuit 1 in series with the primary of-the transformer 5, and the secondary 12 is in. a controlicircuit 13 which is connected-j across part of the quenched spark gap 10. The primary 11 has a small number of turns while the secondary ,12 has a large number of turns, "said coils being inductively connected by being'wound upon a common lron core.

Osmllograms have shown that when certain relations exist between the constants of the various units in Fig. 1, efficient o eration obtains if the spark in the quenche gap 10 occurs at a properly chosen instant when the current 1n the primary of the transformer circuit is in the vicinity of its zero value.

The magnetic flux in the iron core of the series transformer 11, 12 tends to follow the current in the Bpower circuit and since the counter E. M. of the transformer is proportional to the rate of change of the magnetic flux,. the counter E. M. F. is amaximum when the magnetic flux, and therefore the current, passes through the zero value. Thus the voltage on. the secondary 12 of the series transformer will be a maximum when the current in the power circuit passes through zero. The secondary voltage of the control circuit 13 is impressed upon the part of the spark gap 10 to which said circuit is connected and has the effect of increasing the potential gradient on that portion of the spark gap to a value of voltage gradient which compels the production of a spark,

and said circuit acts as a trigger to trip off the main spark across the entire gap at the same instant in each half cycle, so that a uniform sucession of regularly and evenly spaced sparks is produced.

Why this is so, is illustrated by the diagrams of'Figs. 1 and 2 These figures illustrate that portion of the oscillating circuit 4 containing the capacity 6 and spark gap 10, Fig. 2 showing this circuit with the spark control omitted, while Fig. 3 shows the spark control circuit connectedacross a part ofthe spark gap as in Fig. 1. In the curve diagrams shown in connection with each figure, the ordinates are the number of gaps measured from the bottom of the gap 10 as a point of reference, and the abseissae are electro: motive forces measured from the bottom of the gap as a point of reference, the left-hand vertical dotted line passing through zero and the distance between said line and the righthand vertical dotted line representing the electromotive force .from the bottom to the top of the gap 10.

With the control. circuit omitted, as in Fig. 2, the curve, A in the diagram indicates the fall of potential across the gap, and a point on the curve A represents the electromotive .of the condenser, unless the generator is operated at a high field-excitation value.

But where the number of gaps is selected so that the potential. applied each half cycle will cause a single spark, the excitation of the generator above the critical point leads to the production of more than one spark per alternation. But with the usual apparatus an even greater'difliculty is often encountered, to-wit, that of obtaining the sparks of succeeding alternations at the same instant ineach half cycle, or, in other words, at the same point in the voltage wave. Consequently, in the usual arrangements the time intervals between sparks are irregular and a rough or varying note is heard in the receiver. Y

. Now, with the arrangement shown in Fi 3, the control circuit impresses an additional voltage upon a part of the s ark gap, and since the phasing of the tr as related to the transformer 5 is such that the polarity produced by it is, at any in-- stant, opposite to the polarity of transformer 5, the 'electl'omotive force across the lower section of the gap is represented by the curve B which slopes. to the left pf the left-hand vertical dotted line. The main transformer 5 produces across the gaplO an electromotive force E whilethe auxiliary transformer 12 produces across the small section of the gap an electromotive the-discharge'to take place.

. corresponding -curve A in Fig.

-' efiectiv'e increase in the potentiai is: suflicient to causethe gap. to dis force E opposite-in larity to the electromotive force E,.

e sum of these two electromotive forces gives across the up r larger section ofthe gap apotential di erence E which is jlar r thanE number of of gaps to, withstand the smaller electromotive fbrceE when the auxiliary trans;- former isnot- Consequently, sincethe ucesits electromotive orcev Egfor-a s ort interval of time auxilia ana rams: m

as comparedwfith the time of one alternation,

1 n the electrical-strainon, the upper larger se'c-, 5 tion of the gap... v55

I becomes great enough to break do'wngthat-p'art of the gap and, in turn, the smaller section b'reaks' d n The potential $dlellt' acres-the upper larger section-of t 0 gap is represented by the curve C, whose inchnation ismuch greater than that of the 2 and this gradient charge and produce its train of waves.

gap in the;

rent of .t e

ormer 12 .cillations by a spark discharge at while the i p'sto wit standthis larger electromotiveorce Egis less than the number m an oscillatin circuit a normal alternating voltage, an in addition, anaudio freown, allowingated at a normal excitation value below the F critical point and without liability of p11 ducing a plurality of sparks in any one alternation; The trigger control secondary 12 causes its increase in potential gradient across the p each time the primary curwer transformer passes through zero, w ich occurs each alternation. Consequently a condenser discharge occurs each alternation at the instant when the trigger control circuit trips oif the spark and opens the way for, the flow of the main current. Inorder that the potential of the secondary l2 ma in each If cyc e and thereby produce an even succession of sparks the wave form of the secondary is preferably made very peaked by saturating the iron core of the tone control transformer. One suitable form of transformer has a primary of 30 turns and a secondary of 8000 turns, the current in the prima at full load 5 amperes. The core is lhminated, having 48 laminations, .each .014 inch thick, and the magnetic circuit is of rectangular form.

In some cases it may be advisable to occur at a definite instant utilize a suitable capacity 1.5 in the tone con- -trol circuit 13 to limit the amount of current which can flow in the trigger or control circuit 13, but this is not a ways essential and 111 many cases may be omitted.

What I claim is: y

1. The method of producing sparks at regularly recurring intervals, which consists in impressing on a spark ap a normal alternating voltage, and, in ad itlon, an audio frequency volta e impulse at a definite instant in each hafif cycle. of the normal voltage, to thereby down at regular intervals.

2.'The method of producing electrical osg ly recurring intervals, which consists in impressing on part of a quenched spark ga quenc voltage impulse at a definite instant hhalfcytzle' of the normal voltage, to thereby cause said gap to'break downat regular intervals and produce oscillations in the oscillating circuit.

'-'3.;;The method of producing sparks at regularly recurri intervals forgenerati oscillations in a clrcuitcontaining a spar 'gap,iwhich consists in'vapplying to a part r intervals, audio ses derived from the the generator circuit and including cause the gap to breakios moms? part of said gap for impressing an audio frequency voltage impulse thereon to break down said gap at regular intervals.

5. Apparatus for producing oscillations, comprising an oscillating circuit containing a spark gap, a generator circuit for supplying power thereto, and a circuit connecting sald ower circuit and part of said spark gap or applying a single audio frequency vo tage impulse periodically to the gap and thereby breaking it down at regular inn tervals.

6. Apparatus for producing oscillations, comprising an oscillating circuit containing a spark gap, a generator circuit, a transformer connectin said circuits, a circuit including part oi said gap, and a transformer in series with the first-named transformer and including a secondary connected across part of said p, said second transformer producing single audio frequency impulses which are impressed directly upon the spark gap and break down said gap at regular intervals. v

7. The method of producing sparks at regularly recurring intervals in an oscillating circuit containing a spark gap, which consists in impressing an alternating voltage upon'said circuit, and impressing a single audio frequency impulse derived from the main alternating current source upon the spark gap at a definite instant in each half cycle of the alternating voltage.

8. The method of producing sparks at regularly recurring intervals in an oscillating circuit containing an air gap which consists in impressing an alternating volta e upon said circuit and impressing an additional voltage upon a portion of the spark gap at a-definite instant in each half cycle of the alternating voltage, the polarity of the extra voltage being opposite to the po- -larity of the main voltage at the instant it is impressed upon the spark gap. v

9. The method of producing sparks at regularly recurring intervals in an oscillating circuit havin a quenched spark gap which consists in impressing an alternatlng voltage upon saidcircuit and impressing an audio frequency voltage impulse derivedfrom the main alternating current source upon a part ofthe quenched spark gap at a definite instant in each half cycle of the alternating voltage thereby causing said gap to break down at'regular intervals and produce oscillations in the oscillating circuit.

10. The method of producing sparks at regularly recurring intervals in an oscillating circuit having a quenched spark gap which consists in impressing alternating voltage upon said circuit and impressing an extra voltage upon a part of the quenched spark ga at a definite instant in each half cycle oft e alternating voltage, the polarity of the extra voltage being iopposedto that of the main voltage at the instant it is im-v tripped ofi at regular intervals. 11. Apparatus for producin cuit containing a spark gap, a generator circuit for supplying alternating volta e thereto and means for impressing a sing e audio frequency voltage impulse, derived from the main alternating current source, upon a portion of the s ark ga at a definite instant in each hal cycle oi the alternating voltage applied to the oscillating circuit.

12. Apparatus for producin electrical oscillations comprising an osc1 lating circuit containing a spark gap, a generator circuit for supplying power thereto, and means for impressing an extra voltage-upon a portion of the spark gap at a definite instant in each half cycle of the alternating voltage applied to the oscillating circuit, said extra voltage being of opposite polarity to the main voltage at the instant it is impressed. f 13. Apparatus for producing electrical oscillations comprisin' an oscillating circuitcontaining a spar gap, an alternating current generator circuit for supplying power thereto, and means energized by the ,generator circuit for impressing an audio ,rPOWGI thereto, and means energized by the generator circuit for impressing an extra voltage upon a portion of the spark gap at a definite instant in each half cycle of the alternating potential, said extra voltage bepressed on the gap whereby the gap is I electrical oscillations COIIIPI'lSlIlg an osc1 lating 01ring of opposite polarity to that of the main voltage at the instant 1t is impressed.

15. Apparatus for producing electrical oscillations comprising an. oscillating circuit containing a spark gap, an alternating current generator circuit for supplying power thereto, and a third circuit 1nductively connected to the generator circuit by a series transformer arranged to give a peaked wave form, said third circuit being connected across a portion of thespark gap, whereby an audio frequency voltage impulse is suddenly impressed upon a ortion of the spark gap at a definite instant in each half cycle of the alternatin potential.

16. Apparatus for pro ucing electrical oscillations comprising an oscillating cir- ,c uit containing a spark gap, a generator circuit, inductively connected to the oscillating circuit for supplying alternating energy thereto, a third circuit connected to the genverator circuit by a series transformer adapted to give a-peaked wave form, said tlllld circuit being connected to a rtion of the spark gap so that an extra vo tage of opposite spar gap is suddenly impressed upon a lEolarity to the main voltage across the portion of the sparkgap at a definite instant 10 in each. half cycle to thereby trip 011' the spark gap at regular intervals.

In testimony whereof, I have hereunto set my hand.

FRED H. KROGER. Witnesses: i

REUBEN W. CoUsINs, HENRY Hnnmox BOND. 

